Issues with the Downgrade to 8.0 from 8.1U1 DP

Hi! Apparently the Cyan firmware is out for my 1520 (HK CV) so I decided to downgrade in order to install the firmware! But every time I connect the phone to the NSU it says that it can't read my phone's data! Yes, I can transfer data from/to my PC! I don't know what to do! Should I wait?

P.D: And I tried the XDA's flash tutorial almost the same problem (the program can't connect to the phone)
P.D2: Last week I flashed my phone and it worked! So I guess the problem is Update 1.